A lifter device used for a seat of an automobile or the like is adapted to adjust the height of a seat cushion with respect to a floor by operating an operation handle. Various types of lifter devices have been developed. According to the invention disclosed in JP-A-2017-65484, the height of a seat is adjusted by swinging one end of an operation handle about another end thereof in an upper-lower direction. Accordingly, the height is increased by an operation amount for each operation when the operation handle is operated upward from a neutral position. Such operation of the operation handle is repeated until a sitting person reaches a desired height. Meanwhile, when the operation handle is operated downward from the neutral position, a lock mechanism is released from a locked state and the height is continuously lowered.
In the case of the invention disclosed in JP-A-2017-65484, the operation handle is supported by a rotation shaft at a rotation center thereof in a radial direction. However, the operation handle is not supported effectively in a thrust direction since components are stacked only.
As a result, the operation handle is stably rotated about the rotation shaft in the rotation direction, whereas the operation handle may wobble during operation in a direction orthogonal to the rotation direction, and the operation thereof is not stable. This is because, as described above, a gap may be created at the rotation center of the operation handle due to dimensional errors or variations during assembly of the stacked components in the thrust direction, and the operation of the operation handle becomes unstable in the thrust direction due to influence of the gap even when the gap is small. For this reason, an operation end of the operation handle may wobble in the thrust direction of the rotation shaft when the operation handle is swung in the upper-lower direction, which may make an operator feel that the quality of the product is poor.